/*
 * Copyright (C) 2003, 2004, 2005, 2006, 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "flutter/sky/engine/platform/graphics/Color.h"

#include "flutter/sky/engine/platform/Decimal.h"
#include "flutter/sky/engine/wtf/Assertions.h"
#include "flutter/sky/engine/wtf/HexNumber.h"
#include "flutter/sky/engine/wtf/MathExtras.h"
#include "flutter/sky/engine/wtf/dtoa.h"
#include "flutter/sky/engine/wtf/text/StringBuilder.h"

namespace blink {

// FIXME: Use C++11 strong enums to avoid static data member with initializer
// definition problems.
const RGBA32 Color::black;
const RGBA32 Color::white;
const RGBA32 Color::darkGray;
const RGBA32 Color::gray;
const RGBA32 Color::lightGray;
const RGBA32 Color::transparent;

static const RGBA32 lightenedBlack = 0xFF545454;
static const RGBA32 darkenedWhite = 0xFFABABAB;

RGBA32 makeRGB(int r, int g, int b) {
  return 0xFF000000 | std::max(0, std::min(r, 255)) << 16 |
         std::max(0, std::min(g, 255)) << 8 | std::max(0, std::min(b, 255));
}

RGBA32 makeRGBA(int r, int g, int b, int a) {
  return std::max(0, std::min(a, 255)) << 24 |
         std::max(0, std::min(r, 255)) << 16 |
         std::max(0, std::min(g, 255)) << 8 | std::max(0, std::min(b, 255));
}

static int colorFloatToRGBAByte(float f) {
  // We use lroundf and 255 instead of nextafterf(256, 0) to match CG's rounding
  return std::max(0, std::min(static_cast<int>(lroundf(255.0f * f)), 255));
}

RGBA32 makeRGBA32FromFloats(float r, float g, float b, float a) {
  return colorFloatToRGBAByte(a) << 24 | colorFloatToRGBAByte(r) << 16 |
         colorFloatToRGBAByte(g) << 8 | colorFloatToRGBAByte(b);
}

RGBA32 colorWithOverrideAlpha(RGBA32 color, float overrideAlpha) {
  RGBA32 rgbOnly = color & 0x00FFFFFF;
  RGBA32 rgba = rgbOnly | colorFloatToRGBAByte(overrideAlpha) << 24;
  return rgba;
}

static double calcHue(double temp1, double temp2, double hueVal) {
  if (hueVal < 0.0)
    hueVal++;
  else if (hueVal > 1.0)
    hueVal--;
  if (hueVal * 6.0 < 1.0)
    return temp1 + (temp2 - temp1) * hueVal * 6.0;
  if (hueVal * 2.0 < 1.0)
    return temp2;
  if (hueVal * 3.0 < 2.0)
    return temp1 + (temp2 - temp1) * (2.0 / 3.0 - hueVal) * 6.0;
  return temp1;
}

// Explanation of this algorithm can be found in the CSS3 Color Module
// specification at http://www.w3.org/TR/css3-color/#hsl-color with further
// explanation available at http://en.wikipedia.org/wiki/HSL_color_space

// all values are in the range of 0 to 1.0
RGBA32 makeRGBAFromHSLA(double hue,
                        double saturation,
                        double lightness,
                        double alpha) {
  const double scaleFactor = nextafter(256.0, 0.0);

  if (!saturation) {
    int greyValue = static_cast<int>(lightness * scaleFactor);
    return makeRGBA(greyValue, greyValue, greyValue,
                    static_cast<int>(alpha * scaleFactor));
  }

  double temp2 = lightness < 0.5
                     ? lightness * (1.0 + saturation)
                     : lightness + saturation - lightness * saturation;
  double temp1 = 2.0 * lightness - temp2;

  return makeRGBA(
      static_cast<int>(calcHue(temp1, temp2, hue + 1.0 / 3.0) * scaleFactor),
      static_cast<int>(calcHue(temp1, temp2, hue) * scaleFactor),
      static_cast<int>(calcHue(temp1, temp2, hue - 1.0 / 3.0) * scaleFactor),
      static_cast<int>(alpha * scaleFactor));
}

RGBA32 makeRGBAFromCMYKA(float c, float m, float y, float k, float a) {
  double colors = 1 - k;
  int r = static_cast<int>(nextafter(256, 0) * (colors * (1 - c)));
  int g = static_cast<int>(nextafter(256, 0) * (colors * (1 - m)));
  int b = static_cast<int>(nextafter(256, 0) * (colors * (1 - y)));
  return makeRGBA(r, g, b, static_cast<float>(nextafter(256, 0) * a));
}

// originally moved here from the CSS parser
template <typename CharacterType>
static inline bool parseHexColorInternal(const CharacterType* name,
                                         unsigned length,
                                         RGBA32& rgb) {
  if (length != 3 && length != 6)
    return false;
  unsigned value = 0;
  for (unsigned i = 0; i < length; ++i) {
    if (!isASCIIHexDigit(name[i]))
      return false;
    value <<= 4;
    value |= toASCIIHexValue(name[i]);
  }
  if (length == 6) {
    rgb = 0xFF000000 | value;
    return true;
  }
  // #abc converts to #aabbcc
  rgb = 0xFF000000 | (value & 0xF00) << 12 | (value & 0xF00) << 8 |
        (value & 0xF0) << 8 | (value & 0xF0) << 4 | (value & 0xF) << 4 |
        (value & 0xF);
  return true;
}

bool Color::parseHexColor(const LChar* name, unsigned length, RGBA32& rgb) {
  return parseHexColorInternal(name, length, rgb);
}

bool Color::parseHexColor(const UChar* name, unsigned length, RGBA32& rgb) {
  return parseHexColorInternal(name, length, rgb);
}

bool Color::parseHexColor(const String& name, RGBA32& rgb) {
  unsigned length = name.length();

  if (!length)
    return false;
  if (name.is8Bit())
    return parseHexColor(name.characters8(), name.length(), rgb);
  return parseHexColor(name.characters16(), name.length(), rgb);
}

String Color::serializedAsCSSComponentValue() const {
  StringBuilder result;
  result.reserveCapacity(32);
  bool colorHasAlpha = hasAlpha();
  if (colorHasAlpha)
    result.appendLiteral("rgba(");
  else
    result.appendLiteral("rgb(");

  result.appendNumber(static_cast<unsigned char>(red()));
  result.appendLiteral(", ");

  result.appendNumber(static_cast<unsigned char>(green()));
  result.appendLiteral(", ");

  result.appendNumber(static_cast<unsigned char>(blue()));
  if (colorHasAlpha) {
    result.appendLiteral(", ");

    NumberToStringBuffer buffer;
    const char* alphaString =
        numberToFixedPrecisionString(alpha() / 255.0f, 6, buffer, true);
    result.append(alphaString, strlen(alphaString));
  }

  result.append(')');
  return result.toString();
}

String Color::serialized() const {
  if (!hasAlpha()) {
    StringBuilder builder;
    builder.reserveCapacity(7);
    builder.append('#');
    appendByteAsHex(red(), builder, Lowercase);
    appendByteAsHex(green(), builder, Lowercase);
    appendByteAsHex(blue(), builder, Lowercase);
    return builder.toString();
  }

  StringBuilder result;
  result.reserveCapacity(28);

  result.appendLiteral("rgba(");
  result.appendNumber(red());
  result.appendLiteral(", ");
  result.appendNumber(green());
  result.appendLiteral(", ");
  result.appendNumber(blue());
  result.appendLiteral(", ");

  if (!alpha())
    result.append('0');
  else {
    result.append(Decimal::fromDouble(alpha() / 255.0).toString());
  }

  result.append(')');
  return result.toString();
}

String Color::nameForRenderTreeAsText() const {
  if (alpha() < 0xFF)
    return String::format("#%02X%02X%02X%02X", red(), green(), blue(), alpha());
  return String::format("#%02X%02X%02X", red(), green(), blue());
}

Color Color::light() const {
  // Hardcode this common case for speed.
  if (m_color == black)
    return lightenedBlack;

  const float scaleFactor = nextafterf(256.0f, 0.0f);

  float r, g, b, a;
  getRGBA(r, g, b, a);

  float v = std::max(r, std::max(g, b));

  if (v == 0.0f)
    // Lightened black with alpha.
    return Color(0x54, 0x54, 0x54, alpha());

  float multiplier = std::min(1.0f, v + 0.33f) / v;

  return Color(static_cast<int>(multiplier * r * scaleFactor),
               static_cast<int>(multiplier * g * scaleFactor),
               static_cast<int>(multiplier * b * scaleFactor), alpha());
}

Color Color::dark() const {
  // Hardcode this common case for speed.
  if (m_color == white)
    return darkenedWhite;

  const float scaleFactor = nextafterf(256.0f, 0.0f);

  float r, g, b, a;
  getRGBA(r, g, b, a);

  float v = std::max(r, std::max(g, b));
  float multiplier = std::max(0.0f, (v - 0.33f) / v);

  return Color(static_cast<int>(multiplier * r * scaleFactor),
               static_cast<int>(multiplier * g * scaleFactor),
               static_cast<int>(multiplier * b * scaleFactor), alpha());
}

Color Color::combineWithAlpha(float otherAlpha) const {
  return colorWithOverrideAlpha(rgb(), (alpha() / 255.f) * otherAlpha);
}

static int blendComponent(int c, int a) {
  // We use white.
  float alpha = a / 255.0f;
  int whiteBlend = 255 - a;
  c -= whiteBlend;
  return static_cast<int>(c / alpha);
}

const int cStartAlpha = 153;     // 60%
const int cEndAlpha = 204;       // 80%;
const int cAlphaIncrement = 17;  // Increments in between.

Color Color::blend(const Color& source) const {
  if (!alpha() || !source.hasAlpha())
    return source;

  if (!source.alpha())
    return *this;

  int d = 255 * (alpha() + source.alpha()) - alpha() * source.alpha();
  int a = d / 255;
  int r = (red() * alpha() * (255 - source.alpha()) +
           255 * source.alpha() * source.red()) /
          d;
  int g = (green() * alpha() * (255 - source.alpha()) +
           255 * source.alpha() * source.green()) /
          d;
  int b = (blue() * alpha() * (255 - source.alpha()) +
           255 * source.alpha() * source.blue()) /
          d;
  return Color(r, g, b, a);
}

Color Color::blendWithWhite() const {
  // If the color contains alpha already, we leave it alone.
  if (hasAlpha())
    return *this;

  Color newColor;
  for (int alpha = cStartAlpha; alpha <= cEndAlpha; alpha += cAlphaIncrement) {
    // We have a solid color.  Convert to an equivalent color that looks the
    // same when blended with white at the current alpha.  Try using less
    // transparency if the numbers end up being negative.
    int r = blendComponent(red(), alpha);
    int g = blendComponent(green(), alpha);
    int b = blendComponent(blue(), alpha);

    newColor = Color(r, g, b, alpha);

    if (r >= 0 && g >= 0 && b >= 0)
      break;
  }
  return newColor;
}

void Color::getRGBA(float& r, float& g, float& b, float& a) const {
  r = red() / 255.0f;
  g = green() / 255.0f;
  b = blue() / 255.0f;
  a = alpha() / 255.0f;
}

void Color::getRGBA(double& r, double& g, double& b, double& a) const {
  r = red() / 255.0;
  g = green() / 255.0;
  b = blue() / 255.0;
  a = alpha() / 255.0;
}

void Color::getHSL(double& hue, double& saturation, double& lightness) const {
  // http://en.wikipedia.org/wiki/HSL_color_space. This is a direct copy of
  // the algorithm therein, although it's 360^o based and we end up wanting
  // [0...1) based. It's clearer if we stick to 360^o until the end.
  double r = static_cast<double>(red()) / 255.0;
  double g = static_cast<double>(green()) / 255.0;
  double b = static_cast<double>(blue()) / 255.0;
  double max = std::max(std::max(r, g), b);
  double min = std::min(std::min(r, g), b);

  if (max == min)
    hue = 0.0;
  else if (max == r)
    hue = (60.0 * ((g - b) / (max - min))) + 360.0;
  else if (max == g)
    hue = (60.0 * ((b - r) / (max - min))) + 120.0;
  else
    hue = (60.0 * ((r - g) / (max - min))) + 240.0;

  if (hue >= 360.0)
    hue -= 360.0;

  // makeRGBAFromHSLA assumes that hue is in [0...1).
  hue /= 360.0;

  lightness = 0.5 * (max + min);
  if (max == min)
    saturation = 0.0;
  else if (lightness <= 0.5)
    saturation = ((max - min) / (max + min));
  else
    saturation = ((max - min) / (2.0 - (max + min)));
}

Color colorFromPremultipliedARGB(RGBA32 pixelColor) {
  int alpha = alphaChannel(pixelColor);
  if (alpha && alpha < 255) {
    return Color::createUnchecked(redChannel(pixelColor) * 255 / alpha,
                                  greenChannel(pixelColor) * 255 / alpha,
                                  blueChannel(pixelColor) * 255 / alpha, alpha);
  } else
    return Color(pixelColor);
}

RGBA32 premultipliedARGBFromColor(const Color& color) {
  unsigned pixelColor;

  unsigned alpha = color.alpha();
  if (alpha < 255) {
    pixelColor =
        Color::createUnchecked((color.red() * alpha + 254) / 255,
                               (color.green() * alpha + 254) / 255,
                               (color.blue() * alpha + 254) / 255, alpha)
            .rgb();
  } else
    pixelColor = color.rgb();

  return pixelColor;
}

}  // namespace blink
